The present invention relates to a clutch control method of a gear type automatic transmission unit and, more particularly, a technology for improving the reliability of the clutch in the fault operation of the gear type automatic transmission unit.
In the prior art, as the control method of the gear type automatic transmission unit, there are the methods as disclosed in the Unexamined Japanese Patent Application Publication No. Sho 63-270252, etc., for example. In this method, the driving force of the engine is input into the gear type automatic transmission unit by turning ON/OFF the electromagnetic clutch. Then, the switching of the speed changing gear stage is performed by driving the selecting three-position hydraulic cylinder based on operational combinations of a pair of hydraulic solenoid valves to select the transmission gear, and then driving the shifting three-position hydraulic cylinder based on the operational combinations of a pair of hydraulic solenoid valves.
In the event that the failure of the gear type automatic transmission unit disables the transmission operation, its operable condition must be maintained as long as possible as the emergency evacuation. At this time, it is of course that, since the transmission stage is fixed, all operations such as starting, running, stopping, etc. required for the traveling of the vehicle must be handled by only one transmission stage. In other words, when the gear stage is fixed to the second speed range, the third speed range, the fourth speed range, or the fifth speed range by the fault, the vehicle must be started by using such fixed transmission stage.
When the transmission stage is fixed to the second speed range, the third speed range, the fourth speed range, or the fifth speed range, the driving force is smaller than the first speed range. Therefore, the clutch must be engaged for a longer time until the vehicle is started. As a consequence, if the same clutch engagement as the first speed range is carried out in the second speed range, the third speed range, the fourth speed range, or the fifth speed range, such a time is extended that either the output side (transmission unit side) of the clutch can not be rotated even when the input side (engine side) of the clutch is rotated, or difference in the number of rotation between the input side and the output side of the clutch, i.e., the clutch slipping is caused. Thus, the problem is caused that, if such clutch slipping is generated for a long while, the failure of the clutch unit is generated due to the wear or the heat generation of the engaging surfaces of the clutch.
The present invention has been made to overcome the above-mentioned problem, and it is an object of the present invention to suppress the clutch slipping in engaging the clutch and to thus prevent the failure of the clutch, when the failure of a gear type automatic transmission unit disables the transmission operation.
The invention set forth in aspect 1 has such an aspect that a gear type automatic transmission system comprises a gear type automatic transmission unit for sensing at least a shiftxc2x7select position of a gear transmission stage and automatically switching a gear into a target transmission stage by a gear switching actuator; and a clutch for transmitting or cutting off a power from an output shaft of an engine to an input shaft of the gear type automatic transmission unit; wherein clutch engagement is carried out more quickly than a normal operation upon starting in a fault operation of the gear type automatic transmission unit.
The invention set forth in aspect 2 has such an aspect that, in the invention set forth in aspect 1, clutch engagement to cause a vehicle to run at a creeping speed (creep) without depression of an accelerator pedal (partial clutch engagement) can be inhibited in the fault operation of the gear type automatic transmission unit.
The invention set forth in aspect 3 has such an aspect that a method of controlling a gear type automatic transmission system comprises the steps of sensing at least a shiftxc2x7select position of a gear transmission stage; switching automatically a gear of a gear type automatic transmission unit into a target transmission stage; and transmitting or cutting off a power from an output shaft of an engine to an input shaft of the gear type automatic transmission unit by a clutch; wherein clutch engagement is carried out more quickly than a normal operation upon starting in a fault operation of the gear type automatic transmission unit.
The invention set forth in aspect 4 has such an aspect that, in the invention set forth in aspect 3, clutch engagement to cause a vehicle to run at a creeping speed (creep) without depression of an accelerator pedal (partial clutch engagement) can be inhibited in the fault operation of the gear type automatic transmission unit.